Electrically induced anisotropy in nanospheres dispersions

Significant anisotropy can be reversibly induced in aqueous suspensions of highly charged latex spheres of about 10 and 20 nm radius by the application of an electric field. For the first time, information is extracted from the rise time of the induced birefringence. The stationary value of the induced birefringence is found to increase with ionic strength, contrasting with what has been observed for non-spherical particles. These results, unexpected on the basis of commonly used particle–field interaction theories, are interpretated as the consequence of a collective reorganization of the system resulting from the electrically induced anisotropy in the particle–particle interactions.